graph/Tree.cpp

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• Last update: 2021-09-12 23:44:25+09:00

Depends on

• template/template.cpp

Code

#pragma once
#include "../template/template.cpp"

struct Tree {
    vector<int> depth, sub;
    vector<vector<int>> G;
    vector<int> par[20];
    void dfs(int x, int p) {
        sub[x] = 1;
        for (int i : G[x])
            if (i != p) {
                depth[i] = depth[x] + 1;
                par[0][i] = x;
                dfs(i, x);
                sub[x] += sub[i];
            }
    }
    int lca(int x, int y) {
        if (depth[x] > depth[y]) swap(x, y);
        rep(i, 20) if ((depth[y] - depth[x]) >> i & 1) y = par[i][y];
        if (x == y) return x;
        for (int i = 19; i >= 0; i--)
            if (par[i][x] != par[i][y]) {
                x = par[i][x];
                y = par[i][y];
            }
        return par[0][x];
    }
    Tree(vector<vector<int>> G, int root = 0) : G(G) {
        int N = G.size();
        depth.resize(N);
        sub.resize(N);
        rep(i, 20) par[i].resize(N);
        dfs(root, root);
        rep(i, 19) rep(j, N) {
            if (par[i][j] == -1)
                par[i + 1][j] = -1;
            else
                par[i + 1][j] = par[i][par[i][j]];
        }
    }
};

#line 2 "template/template.cpp"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < n; i++)
#define REP(i, n) for (int i = 1; i < n; i++)
#define rev(i, n) for (int i = n - 1; i >= 0; i--)
#define REV(i, n) for (int i = n - 1; i > 0; i--)
#define all(v) v.begin(), v.end()
#define PL pair<ll, ll>
#define PI pair<int, int>
#define pi acos(-1)
#define len(s) (int)s.size()
#define compress(v) \
    sort(all(v));   \
    v.erase(unique(all(v)), v.end());
#define comid(v, x) lower_bound(all(v), x) - v.begin()

template<class T>
using prique=priority_queue<T,vector<T>,greater<>>;

template <class T, class U>
inline bool chmin(T &a, U b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T, class U>
inline bool chmax(T &a, U b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
constexpr ll inf = 3e18;
#line 3 "graph/Tree.cpp"

struct Tree {
    vector<int> depth, sub;
    vector<vector<int>> G;
    vector<int> par[20];
    void dfs(int x, int p) {
        sub[x] = 1;
        for (int i : G[x])
            if (i != p) {
                depth[i] = depth[x] + 1;
                par[0][i] = x;
                dfs(i, x);
                sub[x] += sub[i];
            }
    }
    int lca(int x, int y) {
        if (depth[x] > depth[y]) swap(x, y);
        rep(i, 20) if ((depth[y] - depth[x]) >> i & 1) y = par[i][y];
        if (x == y) return x;
        for (int i = 19; i >= 0; i--)
            if (par[i][x] != par[i][y]) {
                x = par[i][x];
                y = par[i][y];
            }
        return par[0][x];
    }
    Tree(vector<vector<int>> G, int root = 0) : G(G) {
        int N = G.size();
        depth.resize(N);
        sub.resize(N);
        rep(i, 20) par[i].resize(N);
        dfs(root, root);
        rep(i, 19) rep(j, N) {
            if (par[i][j] == -1)
                par[i + 1][j] = -1;
            else
                par[i + 1][j] = par[i][par[i][j]];
        }
    }
};

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